Advancement in robot programming with specific reference to graphical methods

This research study is concerned with the derivation of advanced robot programming methods. The methods include the use of proprietary simulation modelling and design software tools for the off-line programming of industrial robots. The study has involved the generation of integration software to facilitate the co-operative operation of these software tools. The three major researcli'themes7of "ease of usage", calibration and the integration of product design data have been followed to advance robot programming. The "ease of usage" is concerned with enhancements in the man-machine interface for robo t simulation systems in terms of computer assisted solid modelling and computer assisted task generation. Robot simulation models represent an idealised situation, and any off-line robot programs generated from'them may contain'discrepancies which could seriously effect thq programs' performance; Calibration techniques have therefore been investigated as 'a method of overcoming discrepancies between the simulation model and the real world. At the present time, most computer aided design systems operate as isolated islands of computer technology, whereas their product databases should be used to support decision making processes and ultimately facilitate the generation of machine programs. Thus the integration of product design data has been studied as an important step towards truly computer integrated manufacturing. The functionality of the three areas of study have been generalised and form the basis for recommended enhancements to future robot programming systems

Multi-object recognition and retrieval using Puma560 robot

The objective of the research described here is to develop efficient algorithm and software tools for multiobject recognition and retrieval. This research project addresses two major issues: The first issue is the identification of features and efficient methods for feature extraction which can completely describe an object. These features can be acquired using visual and ultra-sonic sensors. The second issue is the development of efficient algorithms for the retrieval of multi-objects based on their features; The methods and algorithms developed in this research are verified on a Unimation PUMA 560 robot. Non contact sensors (a vision and a range sensor) are employed for feature detection. The information from both sensors will be combined for feature extraction and feature mapping (sensor fusion). The sensors and the robot have been integrated for this purpose with a Pentium 133 Mhz Personal Computer

Compensation of Relevant and Compensable Volumetric Errors for Five-Axis Machine Tools Based on Differential Kinematics

RÉSUMÉ Les erreurs géométriques d’une machine-outil ont un impact direct sur la précision des pièces usinées. Cette thèse traite de la compensation d'erreur des machines-outils CNC à cinq-axe. Dans la première phase, une formulation générale de l’erreur volumétrique et un système de compensation hors ligne sont proposés pour améliorer la précision de la pièce. En utilisant la cinématique des corps rigides et les paramètres d'erreur estimés de la machine, les commandes de position de la machine contenues dans un code G standard sont utilisées pour calculer l’erreur de position de l'outil. Le Jacobien, exprimant le différentiel entre l’espace articulaire et l'espace cartésien, est également développé et utilisé pour calculer les modifications de commande articulaire de telle sorte que l'effet des erreurs de la machine peut être annulé par de petits changements directement sur le code G. Lorsque la compensation est implémentée, sa validation est requise. Des machines à mesurer tridimensionnelles (MMT) ou d'autres dispositifs de mesure externes sont couramment utilisés pour mesurer la précision de la pièce usinée à des fins de validation. Dans ce travail, une série de tests de défauts surfaciques issus de l’usinage sont proposés pour comparer la précision d'usinage avant et après la compensation en utilisant des mesures sur machine seulement. Les écarts sur les surfaces produites découlent de l'erreur volumétrique et proviennent d’erreurs géométriques spécifiques de la machine qui sont mesurées en utilisant un palpeur placé sur la machine erronée elle-même. L'effet de la stratégie de compensation est ensuite validé en comparant l’écart entre les surfaces avec usinage compensé et non compensé. Les résultats des mesures sont compatibles avec les valeurs d'erreur volumétrique prévues et montrent une amélioration de la précision (réduction de décalage) d'environ 90% après compensation. Finalement, deux nouvelles notions, la pertinence de l'erreur et l’aptitude à la compenser, sont introduites et quantifiées pour la machine-outil. La compensation des erreurs pertinentes et compensables seulement conduit à une compensation optimisée dans laquelle des modifications de commandes minimales mais efficaces sont faites. Une pièce est conçue spécialement pour le test, contenant des caractéristiques communes est usinée, en utilisant les cinq axes d’usinage simultanément, pour la validation expérimentale. Les résultats de simulation montrent jusqu'à 75% de réduction dans la 1-norme des compensations linéaires et angulaires alors que les erreurs pertinentes demeurent efficacement corrigées.----------ABSTRACT Machine tool geometric errors directly impact on the accuracy of machined parts. This thesis addresses the error compensation in five-axis CNC machine tools. In the first phase, a general volumetric error formulation and an off-line compensation scheme are proposed to improve part accuracy. Using rigid body kinematics and estimated machine error parameters, the machine position commands contained in a standard G-code are used to calculate the tool erroneous location. The Jacobian, expressing the differential joint space to Cartesian space relationship, is also developed and used to calculate minute joint command modifications so that the effect of machine errors can be canceled by making small changes directly to the G-code. When compensation is implemented, its validation is sought. Coordinate measuring machines (CMM) or other external measurement devices are commonly used to measure the accuracy of the machined part for validation purpose. In this work, a series of surface mismatch producing machining tests are proposed to compare the machining accuracy before and after the compensation using only on-machine measurements. The produced surface mismatches that represent the volumetric error and come from specific machine geometric errors are measured using touch probing by the erroneous machine itself. The effect of the compensation strategy is then validated by comparing the surface mismatch value for compensated and uncompensated slots. The measurement results are compatible with the predicted volumetric error values and show an accuracy improvement (mismatch reduction) of about 90 % after compensation for the machine tested. Finally, two new notions, error relevance and error compensability, are introduced and quantified. Compensation of only relevant and compensable errors leads to an optimized compensation in which minimal but effective command modifications are made. A specially designed test part containing common features is machined, using up to five-axis simultaneous machining, for the experimental validation. Simulation results show up to 75% reduction in the 1-norm of the linear and angular compensations while the relevant errors are still effectively corrected

Discrete Assemblers Utilizing Conventional Motion Systems

An alternative to additive manufacturing is disclosed, introducing an end-to-end workflow in which discrete building blocks are reversibly joined to produce assemblies called digital materials. Described is the design of the bulk-material building blocks and the devices that are assembled from them. Detailed is the design and implementation of an automated assembler, which takes advantage of the digital material structure to avoid positioning errors within a large tolerance. To generate assembly sequences, a novel CAD/CAM workflow is described for designing, simulating, and assembling digital materials. The structures assembled using this process have been evaluated, showing that the joints perform well under varying conditions and that the assembled structures are functionally precise

Enhanced online programming for industrial robots

The use of robots and automation levels in the industrial sector is expected to grow, and is driven by the on-going need for lower costs and enhanced productivity. The manufacturing industry continues to seek ways of realizing enhanced production, and the programming of articulated production robots has been identified as a major area for improvement. However, realizing this automation level increase requires capable programming and control technologies. Many industries employ offline-programming which operates within a manually controlled and specific work environment. This is especially true within the high-volume automotive industry, particularly in high-speed assembly and component handling. For small-batch manufacturing and small to medium-sized enterprises, online programming continues to play an important role, but the complexity of programming remains a major obstacle for automation using industrial robots. Scenarios that rely on manual data input based on real world obstructions require that entire production systems cease for significant time periods while data is being manipulated, leading to financial losses. The application of simulation tools generate discrete portions of the total robot trajectories, while requiring manual inputs to link paths associated with different activities. Human input is also required to correct inaccuracies and errors resulting from unknowns and falsehoods in the environment. This study developed a new supported online robot programming approach, which is implemented as a robot control program. By applying online and offline programming in addition to appropriate manual robot control techniques, disadvantages such as manual pre-processing times and production downtimes have been either reduced or completely eliminated. The industrial requirements were evaluated considering modern manufacturing aspects. A cell-based Voronoi generation algorithm within a probabilistic world model has been introduced, together with a trajectory planner and an appropriate human machine interface. The robot programs so achieved are comparable to manually programmed robot programs and the results for a Mitsubishi RV-2AJ five-axis industrial robot are presented. Automated workspace analysis techniques and trajectory smoothing are used to accomplish this. The new robot control program considers the working production environment as a single and complete workspace. Non-productive time is required, but unlike previously reported approaches, this is achieved automatically and in a timely manner. As such, the actual cell-learning time is minimal

SURFACE ENHANCED RAMAN SPECTROSCOPY (SERS) AS AN APPROACH FOR THE EMERGING LIQUID BIOPSY DIAGNOSTICS

Large Molecule bioanalysis and biosensor development are essential techniques that are required in many applications, including biotherapeutic development, in vitro diagnostic, biomarker detection, and early detection. These techniques should be highly specific and sensitive enough to identify and quantify an analyte of interest with minimum sample pretreatment requirements. This work explores the development and application of chip-scale bioassays based on surface-enhanced Raman scattering (SERS). It introduces sensing techniques to quantify various disease biomarkers, specifically pancreatic cancer. Blood is the best source of information about our body\u27s function. There are many biomarkers in the blood, and each biomarker\u27s high expression level can be referred to as a specific disorder. In this work, we have developed sensitive detecting methods to quantify these biomarkers. We successfully validated this method with human serum samples. Due to its capability to detect multiple biomarkers, the proposed bioanalytical technique can enhance the specificity of the approach enabled by machine learning based data classification algorithm

Geometric error compensation software in an open architecture, PC-based machine tool controller

A project was initiated at the Oak Ridge Y-12 Plant to implement software geometric error compensation within a PC-based machine tool controller from Manufacturing Data Systems, Inc. This project may be the first in which this type of compensation system was implemented in a commercially available machine tool controller totally in software. Previous implementations typically required using an external computer and hardware to interface through the position feedback loop of the controller because direct access to the controller software was not available. A mathematical error model of the lathe was created using homogeneous matrix transforms to relate the positions of the machine\u27s slides to each other and to a world reference system. Equations describing the effects of the geometric errors were derived from the model. A software architecture was developed to support geometric error compensation for machine tools with up to 3 linear axes. Rotary axes were not supported in this implementation, but the developed architecture would not preclude their support in the future. Specific implementations will be dependent upon the configuration of the machine tool. The test-bed machine for this project was a 2-axis Excello 921 T-base lathe. A laser measuring system from Automated Precision, Inc. was used to characterize the lathe\u27s geometric errors as functions of axis position and direction of motion. Multiple data files generated by the laser system were combined into a single Error File that was read at system startup and used by the compensation system to provide real-time position adjustments to the axis servos. A Renishaw Ballbar was used to evaluate the compensation system. Static positioning tests were conducted in an attempt to observe improved positioning accuracy with the compensation system enabled. These tests gave inconsistent results due to the lathe\u27s inability to position the tool repeatably. The development of the architecture and compensation template will provide a baseline platform for investigating other types of error compensation in the future